Error When Publishing a Single File

[Ian Barton <lists@manor-farm.org>]

This has been happening for a while. I suspect it's something in my 
settings, but I can't work out what. When I publish a single file, I get 
the following error:

Debugger entered--Lisp error: (wrong-type-argument arrayp nil)
   file-truename(nil)
 
org-publish-file("/home/ian/nfs/firewall/Documents/org/holiday/holiday.org")
   byte-code("\b?…\x06
   org-publish-current-file(nil)
   call-interactively(org-publish-current-file)
   org-export(nil)
   call-interactively(org-export)

Publishing a whole project works fine. This is the relevant bit of my 
.emacs:

(require 'org-publish)
(setq org-publish-project-alist
       '(

        ;; ... add all the components here (see below)...
       ("org-notes"
           :base-directory "~/nfs/firewall/Documents/org/"
           :base-extension "org"
           :publishing-directory "~/nfs/firewall/public_html/org/"
           :recursive t
           :publishing-function org-publish-org-to-html
           :headline-levels 4             ; Just the default for this 
project.
           :auto-preamble t
           :auto-index t
           :index-filename "sitemap.org"
           :index-title "Sitemap"
       )

     ("org-static"
           :base-directory "~/nfs/firewall/Documents/org/"
           :base-extension 
"css\\|js\\|png\\|jpg\\|gif\\|pdf\\|mp3\\|ogg\\|swf"
           :publishing-directory "~/nfs/firewall/public_html/org/"
           :recursive t
           :publishing-function org-publish-attachment)

     ("org" :components ("org-notes" "org-static"))


       ))